Multi-element wheel alignment shim assembly, and method of use

ABSTRACT

Shim assembly configured to be positioned in a wheel assembly to correct alignment and formed of a plurality of flat, tapered elements securable together and positionally adjustable one relative to the other with selectable orientation of the tapers, preferably rotatably secured for mutual angular movement of the elements around an axis, indicia to display the angular relationship of the elements and of the shim assembly orientation, such that the taper of the elements add or subtract to establish the overall composite taper of the shim assembly with the indicia displaying such composite taper and/or providing orientation points for positioning of the shim assembly in a wheel assembly to correct alignment.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates broadly the wheel alignment for vehicles,and more particularly to tapered shim elements configured to be securedtogether into a shim assembly which can be positioned as a single,unitary component to alter and correct the relative position of an axleor spindle and, ultimately, of a wheel carried on such axle or spindle.

2. Related Art

The concept of utilizing one or more thin, identical tapered shimelements interposed substantially perpendicular to the axis of an axleor spindle is old and well developed. Much effort has been expended withlimited success to minimize the differing embodiments of such shimelements required to fit numerous vehicle models and to provide fine andaccurate correction of a wide range of misalignment conditions. Also,emphasis has been placed at simplifying both selection of theappropriate corrective taper and actual installation of the tapered shimelement under confined and difficult circumstances.

Such tapered shim elements are employed in two fundamentally differingbut related vehicle structures, i.e. at a steerable front wheel, and ata fixed rear wheel. When used at a steerable wheel, the tapered shimelement can be rotated around the wheel axis when adjusting camber suchthat the taper is orthogonally resolved into camber and toe components.When the appropriate camber correction is realized, the toe componentcan be easily accommodated by the toe correction mechanism provided atsteerable wheels, i.e. tie rod length adjustment. However, at fixed rearwheels the toe and camber must both be set by selecting a tapered shimelement of just the proper taper, and resolving the camber and toecomponents to precisely correct both of the alignment settings. Inpractice this means the shim element must have a single proper taper,and that such taper must be properly oriented relative to toe andcamber. Otherwise, two independent shim elements may be needed andstacked with the taper of one shim element oriented to correct toe andwith the taper of the other oriented to correct camber.

U.S. Pat. Nos. 4,037,680 and 4,195,862 describe tapered shim elementsadapted to correct the camber of driven, steerable wheels. Eachdescribes a selection of tapered shim elements from which a choice canbe made to correct wheel camber. The latter patent discusses colorcoded, filled polymer shim elements which seal when stacked with thetaper axis (that which extends from the thin to the thick end of theshim element) in a vertical alignment.

U.S. Pat. No. 4,684,150 describes a set of twelve shim elements, each ofa different taper, which have a series of notches at the peripherythereof. By selecting a shim element of an appropriate taper, and bypositioning the shim element with the appropriate vertical orientation,both camber and toe can be corrected. The open notches allow the shimelement to be repositioned without complete removal of the wheel mount.For greater correction, the shim elements can be stacked.

U.S. Pat. No. 4,872,699 discloses a set of shim elements of differingtapers having a series of frangible tabs around the periphery thereof.By breaking out selected tabs the shim elements can be configured to fitbolt patterns with differing vertical orientations of the shim elements.A comprehensive template system for determining breakout patterns ispresented.

Ingalls Alignment Products has marketed a set of "808 Shims" consistingof two identical one and one-half degree tapered shim elements for usewith fixed rear wheels. For corrections requiring other than a singleone and one-half degree shim element, two individual shim elements areinstalled stacked in accord with a chart utilizing numerical markingsimprinted in each shim element.

U.S. Pat. No. 774,042 discusses an early attempt to use two independenttapered members to correct alignment. However, no means for correlatingmeasured misalignment and tapered member setting are suggested. Thus theconcept, which appears to rely on eyeball corrections, would not beappropriate for modern vehicles.

SUMMARY OF THE INVENTION

The present invention involves an adjustable tapered shim assembly, asopposed to one or more individual shim elements, in which a plurality-preferably two- tapered shim elements are or can be secured together toform a preselected composite taper as a shim assembly. A much preferredembodiment includes a securing the shim elements together whileproviding for relative rotary movement. Each shim element isfunctionally defined by two planar surfaces, comprising at least aportion of a shim element side, which define an angle between the planesof greater than zero. The elements, which are preferably circular, arejoined with planes abutting and preferably rotatable around an axis ator near the centers of the planes, preferably concentrically. Eachsurface may be divided into offset subsurfaces complementary tocorresponding subsurfaces on the other shim element. Thus the shimassembly may be variably adjusted through a range of tapers by rotatingthe elements, either while connected or prior to securing the elementstogether, such that the respective tapers add or subtract one to or fromthe other. Optionally, releasable stops can be provided to position theelements with a predetermined composite taper of the shim assembly. Toassist in releasing the stops, textured areas may be provided toindicate the proper hand position for adjusting the shim assembly.Indicia means may be included to display the amount of composite shimassembly taper as well as orientation of the taper. Thus, in use, avehicle wheel can be measured to determine the degree of toe and cambercorrection required. Then, using an expansive manual lookup chart, ormore conveniently a computer algorithm, the assembly taper andorientation necessary for the correction can be determined (preferablein terms of the indicia on the shim assembly). In view of the power ofthe subject invention to cover a wide array of vehicle models, it may bedesirable to employ an algorithm which calculates composite tapers andpositions using trigonometric functions rather than using a computerversion of the manual lookup chart. Once the two variables areestablished, it is a simple matter to install the preset assembly in thevehicle in the appropriate predetermined orientation. A single shimassembly can correct a full range of misalignments for a large range ofvehicles in a simple, convenient process.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate complete embodiments of theinvention according to the best mode so far devised for the practicalapplication of the principles thereof, and in which:

FIG. 1 is a perspective view of a preferred shim assembly in accord withthe instant invention;

FIG. 2 is a front view of the preferred shim assembly of the embodimentof FIG. 1;

FIG. 3 is a front view of a first tapered shim element of the shimassembly shown in FIG. 1 and FIG. 2;

FIG. 4 is a section view along section line . .A--A.!. .Iadd.4--4.Iaddend.of the first tapered shim element shown in FIG. 3;

FIG. 5 is a front view of a second tapered shim element of the shimassembly shown in FIG. 1 and FIG. 2;

FIG. 6 is a section view along section line . .B--B.!. .Iadd.6--6.Iaddend.of the second tapered shim element shown in FIG. 5;

FIG. 7 is a detailed sectioned view of the rotatable snap connectionbetween the first and second elements shown in FIGS. 2 through 6;

FIG. 8 is an alternative second tapered shim element similar to thatshown in FIG. 5;

FIG. 9 is a front view of a shim element of yet another embodiment ofthe invention;

FIG. 10 is a front view of a shim element configured for use with theelement of FIG. 9;

FIG. 11 is a partial view of a composite shim assembly of the sectionedshim elements of FIG. 9 and FIG. 10; and

FIG. 12 is a view of a typical axle assembly into which the shimassembly of the present invention can be inserted to correct alignment.

DESCRIPTION OF THE INVENTION

Turning now to the drawings, wherein like components are designated bylike reference numerals throughout the various figures and embodiments,a shim assembly according to a particularly preferred embodiment of theinvention is illustrated in FIGS. 1 through 7 and FIG. 12, and isgenerally designated by the reference numeral 10. Shim assembly 10 isformed in part of a first tapered shim element 12 illustrated in moredetail in FIGS. 3 and 4. As shown therein, first tapered shim element 12is circular in shape around an axis 13 with a number of openings 14defined therethrough in a circumferential pattern. Openings 14 areelongated in the circumferential direction to fit vehicle boltarrangements having differing horizontal spacing at different pairs ofconnectors. Also defined on first tapered shim element 12 are taperindicia means 15 and shim assembly orientation indicia means 16.Orientation indicia means 16 are preferably positioned to indicate thetop of tapered shim assembly 10, but alternatively can be positionedadjacent an opening 14 which is thus identified as that which receives avehicle bolt 56 shown in FIG. 12. Shim assembly 10 is designed toaccommodate many vehicle models and thus may not always receive bolt 56in the same opening 14. However, the top or uppermost, position of shimassembly 10 is a constant that does not change with vehicle design asbolt patterns may. Ramp-sided detents 18 are formed in a concentric,circumferential pattern in first tapered shim element 12. And, as shownin FIG. 4, first tapered shim element 12 is formed with a planar frontsurface 20, which is concentric to axis 13, and a planar rear surface 22which are nonparallel and define the taper of first tapered shim element12. Sunken surface 24 is centrally defined in a circular shape andconcentric to axis 13 in front surface 20 of first tapered shim element12. Lip 25 and associated ramp portion 26 define central opening 27,inside of openings 14, which extends through first tapered shim element12.

Shim assembly 10 also includes second tapered shim element 30 which, asillustrated in FIGS. 5 and 6, is circular in shape and of a diameter asto nest within sunken surface 24 inside of openings 14 of first taperedshim element 12 and concentric with axis 13. Textured engaging areas 31are defined in the front surface 34 of second shim element 30 toindicate the proper position at which to hold shim assembly 10 whileadjusting it. Indicator 32 is defined through second tapered shimelement 30 and spaced to display taper indicia means 15 as shown in FIG.. .1.!. .Iadd.7.Iaddend.. Dog 33, in the form of a V-shaped projection,extends from the rear surface 35 of shim element 30, and is radiallyspaced on second tapered shim element 30 to engage detents 18 of firsttapered shim element 12 when assembled as shown in FIG. 1 and FIG. 7.Textured engaging areas 31 are spaced from the position of dog 33 suchthat pressure applied at textured areas 31 will not force dog 33 intodetents 18, thus allowing relative rotation of tapered shim elements 12and 30. Upon application of a mutual torque between first tapered shimelement 12 and second tapered shim element, dog 33 moves up theramp-sided walls of detent 18 and is repositioned in an adjacent detent18. Thus mutual rotation of first tapered shim element 12 and secondtapered shim element 30 may be continued until a reaching a desiredsetting whereupon dog 33 is allowed to engage a detent 18 thuspreserving the setting.

Nonparallel front surface 34 and rear surface 35 are shown in FIG. 6 asare opposed connectors 36, each of which has defined thereon ramp 37 andgroove 38. As depicted in FIG. 7, first tapered shim element 12 andsecond tapered shim element 30 are attached together by connecting meansrotatably securing first shim element 12 to second shim element 30,preferably by inserting connectors 36 of second tapered shim element 30into central opening 27 of first tapered shim element 12 such that lip25 of the latter is positioned in groove 38 of the former. Ramp 37bearing against ramp portion 26 of lip 25 serves to displace connectors36 to facilitate such insertion. Thus shim element 12 bears at sunkensurface 24 against complementary, parallel surface 35 of second shimelement 30, both surfaces 24 and 35 being in extended planes (not shown)concentric to and preferably perpendicular to axis 13. If such planeswere not perpendicular, radial forces could be produced which wouldunnecessarily stress shim assemble 10. As shown, dog 33 fits intodetents 18 to form releasable locking means 41 which releasably positionfirst tapered shim element 12 relative to second tapered shim element 30in predetermined positions which are identified by shim assembly taperdisplay means 39, such as taper indicia means 15 at indicator window 32.Central opening 27 is preferably through first tapered shim element 12to ease tooling requirements, but central opening 27 could operable be ablind opening.

While the embodiment of FIG. 1 is to be preferred in most respects, aportion of the industry desires a "full coverage" design in which theentire shim extends over a maximum amount of the area of the surfacesbetween which it is inserted. This is viewed as a cosmetic concern inthat the area of shim assembly 10 has been shown by finite elementanalysis to be more than adequate to support the pressures developed inuse. However, by substituting a modified second tapered shim element 30'as shown in FIG. 8, a "full coverage" shim assembly can be provided.Second tapered shim element 30' is essentially identical to secondtapered shim element 30 with regard to many features including dog 33and connectors 36, but differs primarily with regard to extended annularsurface 42 in which openings 14' are defined. Indicator 32' isfunctionally identical to indicator 32 but enclosed rather than open atthe top. Extended surfaces 42 each start at step 44, adapted to fitsunken surface 24 of first tapered shim element 12, and continue thetaper of . .taper as.!. second tapered shim element 30. Spokes 46partially defining openings 14' are frangible at sections 48 thereof.Thus second tapered shim element 30' functions much like second taperedshim element 30 of shim assembly . .12.!. .Iadd.10 .Iaddend.except that,upon relative rotation, may be positioned with one or more of spokes 46blocking an opening 14 of first tapered shim element 12 therebypreventing placement of shim assembly . .12.!. .Iadd.10 .Iaddend.onvehicle bolts. This is simply remedied by removing the blocking spokes46 at frangible sections 48 thereof. Since removal of spokes 46 is afunctionally superfluous step, the embodiment of FIG. 1 is preferred.

Still another embodiment of the invention is illustrated in FIGS. 9through 11. Again, shim elements 12' and 30" differ only in detail fromthe corresponding elements of the preferred embodiment. As shown in FIG.9, shim Element 12' in that sunken surface 24' is bounded by centralopening 27' which, in part, is defined by radial indents 29. Shimelement 30", shown in FIG. 10, includes connectors 36' configured toengage radial indents 29. Thus when shim elements 12' and 30" are joinedto form shim assembly 10" as shown in FIG. 11, ramp 37' of connector 36'distends connector 36' sufficiently to allow lip 25' to fit into groove38' thereby securing shim element 12' to shim element 30". If desired,shim assembly 10" can be disassembled by reversing the procedure suchthat second ramp 40 will similarly distend connector 36' and release lip25' from groove 38'. In practice, shim elements 12' and 30" areseverally aligned with the appropriate taper indicia means 15 atindicator window 32. They are then snapped together to form shimassembly 10" with radial indents 29 cooperating with connectors 36' topreserve the relative angular relationship thereof and lip 25' in groove38' serving to secure shim elements 12' and 30" axially. Once securedtogether, shim assembly . .12'.!. .Iadd.10" .Iaddend.is functionallyidentical with the preferred shim assembly . .12.!. .Iadd.10.Iaddend..

A typical single item of shim assembly 10 of FIG. 1, when scaled to anouter diameter of 3.16 inches (8 cm) provides bolt coverage for 39differing vehicle model applications through the typical one andone-half degree adjustment range. While specific vehicle applicationdesign is an iterative process in which mutually compatibleapplications, particularly bolt patterns, are determined essentially bytrial and error, but four different configurations of the embodiment ofshim assembly 10 have been found to cover 86 different models ofvehicles in an initial study.

First tapered shim element 12 and second tapered shim element 30 caneach be formed with the same taper. However, since a zero degreecorrection is seldom needed, it is preferable that the tapers of shimelements 12 and 30 differ. For the usual one and one-half degree total,a one-quarter degree difference in the tapers of shim elements 12 and 30is desirable. Toe correction should be precise to at least one-sixteenthdegree to minimize tire wear, but tire compliance is tolerant of cambermisalignments of one eight-degree. Thus a composite shim assembly 10taper of one-quarter degree can readily be position with one-eighthdegree in the toe -or horizontal- orientation to correct toemisalignment greater than one-sixteenth degree, and the remainder of thetaper resolved into camber change.

In use a vehicle rear wheel assembly 50 is examined on an alignment rackto determine toe and camber misalignment of a wheel (not shown) carriedon spindle 52. The appropriate correction values are . .the.!..Iadd.then .Iaddend.determined by a manual reference noting the side ofthe vehicle on which spindle 52 is mounted, or calculated by computerusing an appropriate algorithm, and settings for taper indicia means 15and shim assembly orientation indicia means 16 determined. Shim assembly10 is then adjusted such that appropriate taper indicia 15 means appearsin indicator window 32 and shim assembly 10 is . .the.!. .Iadd.then.Iaddend.installed in the vehicle between suspension plate 54 andspindle 55 mounted with selected orientation indicia means 16 facingoutward and upward. Bolts 56 (one shown) are then properly torqued. Thusspindle 52 is adjusted by shim assembly 10 relative to suspension plate54 such that toe and/or camber are correct. A single shim assembly 10can be configured to cover the entire adjustment range and is easily andconveniently adjusted and installed. While suspension plate 54 is oftenmounted to an axle, it could of course be mounted to -or be- then hubcarrier of a Chapman strut (not shown), or other suspensionconfiguration.

Shim assembly 10 can be made of metal and/or polymeric materials.Glass-filled poly-caprolactam (nylon) is a particularly desirable one ofthe latter materials. Die casting or injection molding are usefulforming processes which can accommodate connectors 36 without sectioningthe dies or molds. Many other materials and forming processes will beapparent to those skilled in the art.

The above-described preferred variations on the subject shim assemblycan be modified to numerous other embodiments if desired. The describedand illustrated integral means of rotatably connecting the tapered shimelements is advantageous in that only the two elements are necessary.But the shim elements could be oriented as desired and then securedtogether, preferably in a releasable manner, in a fixed, nonrotatablerelationship. The connecting means can alternatively be formed at theouter periphery of the shim assembly, or the elements can be formedwithout a central opening and rotatably or nonrotatably joined by aindependent component such as a rivet or a bolt. In the simplestembodiment, two shim elements each defined at least in part by opposedflat tapered surfaces can be journalled together. The indicia means canappear on a separate template, or the taper indicia means can becalibrated to indicate actual taper in degrees. More than two shimelements can be used. The indicator cooperating with the taper indiciameans could be any marking rather than the preferred window opening. Byway of example, a spacer having a limited bolt hole pattern with but oneopening per bolt and parallel sides can be joined with a rotatabletapered shim element rotatably secured to each side thereof. The amountand orientation of the shim assembly taper thus can be changed withoutthe need to rotate the bolt hole pattern. These and other modificationscan be readily accomplished as circumstances suggest.

Thus, although only a limited preferred embodiment and modificationthereof has been described and illustrated in detail, it is anticipatedthat various other change and modifications will be apparent to thoseskilled in the art, and that such changes and modifications may be madewithout departing from the scope of invention as defined by thefollowing claims.

What is claimed is:
 1. A shim assembly for correcting misalignment oftoe and/or camber of a vehicle wheel spindle extending from a mountingplate attached to a vehicle.Iadd., .Iaddend.the shim assemblycomprising:a first tapered shim element having opposed, nonparalleltapered surfaces; a second tapered shim element having opposed,nonparallel tapered surfaces, at least a portion of one of the taperedsurfaces of the first tapered shim element and at least a portion of oneof the tapered surfaces of the second tapered shim element beingadjacent to and in contact with each other.Iadd., and in which aplurality of spaced apart openings is defined through only one of thefirst and second tapered shim elements and the other of the first andsecond tapered shim elements is positioned inward of theopenings.Iaddend.; and connecting means rotatably securing the firsttapered shim element to the second tapered shim element for mutualrotation around a common axis, whereby the composite taper of the shimassembly may be varied by orienting the taper of the first tapered shimelement relative to the taper of second tapered shim element. . .
 2. Ashim assembly as set forth in claim 1 in which:at least one of the-firstand second tapered shim elements have defined therethrough a pluralityof spaced apart openings..!.. .3. A shim assembly as set forth in claim2 in which: only one of the first and second shim elements have thespaced opening defined therethrough, and the other of the first andsecond shim elements is positioned inward of the openings..!.4. A shimassembly as set forth in claim . .2.!. .Iadd.1 .Iaddend.in which: theopenings in at least one shim element are closed.
 5. A shim assembly asset forth in claim . .2.!. .Iadd.1 .Iaddend.in which:the openings in atleast one shim element extend to the edge of the tapered shim element ..and.!..
 6. A shim assembly as set forth in claim . .2.!. .Iadd.1.Iaddend.in which:the openings are arranged in a circular patternconcentric with the common axis.
 7. A shim assembly as set forth inclaim 1 in which:taper display means are defined on the shim assembly todisplay the angular position of the taper of the first tapered shimelement relative to the taper of the second tapered shim element,whereby the composite taper of the shim assembly can be determined.
 8. Ashim assembly as set forth in claim 7 in which: the taper display meansinclude indicia means defined on one of the tapered shims and indicatormeans defined on the other to indicate the relative taper positions ofthe two shim elements and the resulting composite taper of the shimassembly. . A shim assembly as set for the in claim 8 in which:the taperindicia means are markings arranged in a circular pattern and theindicator means are a window opening defined in the shim element throughwhich a marking is displayed.
 10. A shim assembly as set forth in claim1 in which:a dog projects from the adjacent surface of one of the shimelements; and a plurality of ramp-sided detents are defined in acircular pattern concentric with the common axis in the adjacent surfaceof the other of the shim elements and positioned to releasably receivethe dog in one of the detents, whereby one shim element can bereleasably secured in a selected engagement position relative to theother shim element.
 11. A shim assembly as set forth in claim 10 inwhich:taper indicia means are defined on one of the shim elements; andindicator means are defined on the other shim element with the indiciameans and indicator means positioning corresponding to dog and detentsengagement positions.
 12. A shim assembly as set forth in claim 1 inwhich:taper orientation indicia means are defined on the shim assemblyto indicate the relative position of the composite taper of the shimassembly. . .13. A shim assembly as set forth in claim 1 in which theconnecting means comprise:an arcuate groove defined in one of the shimelements; an arcuate lip defined in the other of the shim elements; atleast two opposed connectors positioned on one of the shim elements, oneof the groove and lip being defined in the connectors on the shimelement and the other of the groove and lip extending to engage thecorresponding groove or lip at at least two opposed connectors at allrotational positions to secure the first and second shim elementstogether as a rotationally adjustable shim assembly..!.. .14. A shimassembly as set forth in claim 13 in which: the groove is defined insections in the connectors and the lip extends as a full circle and isjournalled in the groove sections..!.. .15. A shim assembly as set forthin claim 13 in which: at least one of the groove and lip have definedadjacent thereto a ramp portion..!.16. An adjustable shim assembly forcorrecting wheel alignment, the shim assembly comprising:a first taperedshim element having opposed, at least partially flat, nonparallelsurfaces; a second tapered shim element having opposed, at leastpartially flat, nonparallel surfaces with at least one of the flatsurfaces of the first tapered shim element being in contact with atleast one of the flat surface of the second tapered shim element;connecting means rotatably attaching the first tapered shim element tothe second shim element for rotation around an axis perpendicular to thecontacting surfaces of the first and second tapered shim elements; ..and.!. taper indicia means defined on the shim assembly to display therotational position of the first tapered shim element relative to thesecond tapered shim element and thus the composite taper of the shimassembly.Iadd.; and releasable locking means for indexing and securingthe first and second shim elements at positions corresponding to thetaper indicia means.Iaddend.. . .17. An adjustable shim assembly as setforth in claim 16 in which:taper display means are defined on the shimassembly to display the amount of composite taper of the shimassembly..!.18. An adjustable shim assembly as set forth in . .claims.!..Iadd.claim .Iaddend.16 . .or 17.!. in which:orientation indicia meansare defined on the shim assembly to identify the relative direction ofthe composite taper of the shim assembly. . .19. An adjustable shimassembly as set forth in claim 16 in which: releasable locking means forindexing and securing the first and second shim elements at positionscorresponding to the taper display means..!. A method for compensatingfor wheel misalignment of camber and/or toe in a wheel carried on aspindle assembly releasably secured to . .an.!. .Iadd.a.Iaddend.suspension plate . .at.!. .Iadd.by fasteners connecting.Iaddend.abutting surfaces thereof, comprising:measuring themisalignment of the wheel; adjusting a shim assembly comprising twotapered shim elements rotatably attached one tapered shim element to theother tapered shim element around an axis of rotation.Iadd., one taperedshim element having spaced openings defined therethrough and the othertapered shim element being positioned inside of the openings,.Iaddend.by rotating . .at least.!. one of the shim elements relative tothe other to establish the desired corrective composite taper of theshim assembly; positioning the adjusted shim assembly in a predeterminedorientation between the suspension plate and the spindle assembly; andsecuring the spindle assembly to the suspension plate with the shimassembly therebetween .Iadd.with the securing fasteners extendingthrough the openings in one shim element .Iaddend.to reposition thewheel and spindle assembly relative to the suspension plate with thespindle in proper alignment.
 21. A method for compensating for wheelmisalignment as set forth in claim 20 in which:the shim assemblyincludes taper indicia means defined on one shim element, and indicatormeans defined on the other shim element and the composite taper isdetermined by aligning selected of the taper indicia means with theindicator means.
 22. A method for compensating for wheel misalignment asset forth in claim 21 in which:the taper indicia means comprise aplurality of marking arranged in a circle and the indicator meanscomprise an opening defined in the shim element and the composite taperis determined by positioning a selected one of the markings in the ..window.!. .Iadd.opening.Iaddend..